[Constructing genetic linkage maps in Chinese Fir using F1 progeny]

A new strategy was proposed for constructing linkage maps for 1:1 segregation molecular markers in Chinese fir. Linkage phase and recombination ratio for any two loci can be inferred and estimated. For the best order in a linkage group, the Hidden Markov Chain Model was used for multilocus linkage analysis. The mapping method proposed here was more effective than the 'pseudo-testcross' method commonly used in forest trees. In this paper,with the AFLP marker data obtained from the F1 progeny of 'Jurong 0' (female) x 'Rouye' (male), the genetic linkage maps of the Chinese fir clones, 'Jurong' and 'Rouye', were reconstructed based on the new mapping method. In the genetic linkage map of "Jurong 0", 101 markers were distributed in 11 linkage groups with an average distance of 22.6 cM and a total length of 2 282.6 cM. There were as many as 17 markers and as few as 5 markers in single linkage groups of the map. In the genetic linkage map of 'Rouye', 94 markers were distributed in the 11 linkage groups with an average distance of 27.3 cM and a total length of 2 565.8 cM. There were as many as 16 markers and as few as 4 markers in single linkage groups of the map. Compared with the 'pseudo- testcross' method, the two maps increased 26 markers and 28 markers, respectively, and totally 54 markers were added. The two maps contained 195 AFLP markers and each spanned more than 2 000 cM, almost covering the whole genome of Chinese fir. Therefore, the resolutions of linkage maps of Chinese fir 'Jurong 0' and 'Rouye' were improved with the new mapping method, and the maps provide the framework for further genetic analysis.